A plurality of layers such as polysilicon, oxide, nitride, and metal are deposited on a wafer that is used as a semiconductor substrate in a semiconductor fabricating process. A photoresist layer is coated on the layer. A pattern drawn on a photo mask using an exposure process is transcribed to the photoresist layer. An etching process is carried out to form a desired pattern on the wafer. Foreign substances such as various layers or photoresist remain the top edge or the bottom of a wafer where the above-mentioned processes are carried out. If the edge of a held wafer is transferred, the foreign substances are separated from the wafer to be dispersed. The dispersed substances contaminate an apparatus and act as particles in subsequent processes. Thus, a process for etching the edge of a wafer is required.
Conventionally, among a pattern-formed surface of a wafer, a portion except a to-be-etched wafer edge (hereinafter, the portion being referred to as “non-etch portion”) is protected with a protectant or a mask and then is submerged in a bath filled with an etchant to etch the wafer edge. In the wet etch, an etch rate is higher but a layer is inclined at a boundary portion of the non-etch portion and the edge of the wafer to lower a yield because the wet etch is an isotropic etch. Further, the above-described method includes protecting a pattern-formed portion with a protectant or a mask and re-removing the same, which results in a long work time and consumption of a large amount of etchant.